In recent years, transparent conductive films have been indispensable when manufacturing photoelectric converters such as solar cells. For a conventional transparent conductive film, an indium tin oxide (ITO) film (a tin-doped indium oxide film) is known. The ITO film has the advantages of excellent transparency and low resistance.
Meanwhile, there has been a need for cost reduction in solar cells, liquid crystal display devices, or the like. However, since indium is expensive, when the ITO film was employed as a transparent conductive film, there was a disadvantage in that the solar cell inevitably became expensive as well. In addition, in the case of manufacturing solar cells or the like, an amorphous silicon film is formed on a transparent conductive film by a plasma chemical vapor deposition (CVD) method. At the time, if the transparent conductive film was an ITO film, there was a problem in that hydrogen plasma upon plasma CVD led to deterioration of the ITO film.
In order to solve such problems, it has been proposed that a zinc oxide-based film doped with a conductive active element such as Al, B, or Si which can be prepared with less budget be used as a transparent conductive film such as solar cells or the like, and a zinc oxide-based sputtering target be used to form a zinc oxide-based film by sputtering (for example, see Japanese Unexamined Patent Application No. Hei 6-2130 (claims 2, 3, and 4)). According to this zinc oxide-based sputtering target, an extremely low resistance zinc oxide-based sintered body can be obtained by containing a predetermined amount of the foregoing conductive active element in zinc, and sintering density and conductivity of this sintered body are improved if the raw material powder is fine and has high dispersibility.